Milling tool

ABSTRACT

The milling tool, in one form, has a shank having a shank rotation axis, a first cutting-edge carrier having at least one cutting edge and at least two arched areas and a second cutting-edge carrier having at least one cutting edge and at least two arched areas. The arched areas are shaped and positioned to form a tubular socket in which the shank is attached with both cutting-edge carriers radially projecting in a lobe-like manner from the shank and being rotatable about the shank rotation axis. The at least two arched areas of both cutting-edge carriers are spaced from each other axially, have surfaces normal to the shank rotation axis, arch in the same direction and are displaced from and parallel to the shank rotation axis so that the first and second cutting-edge carriers mutually overlap to form the tubular socket for the shank so that, when the shank is attached in the tubular socket, the cutting-edge carriers are locked against each other.

BACKGROUND OF THE INVENTION

The invention relates to a milling tool.

A milling tool is known having a shank to which a substantially flatfirst cutting-edge carrier having at least one cutting edge is fastenedin a radially projecting, lobe-like manner. The cutting-edge carrier isintended to rotate about a crrier rotation axis located in its plane.

German Patent Specification 2,523,201 has already disclosed a two-piecespade drill. This spade drill consists of a cylindrical shank which isslit at the end face so that it roughly has the shape of a fork with twoprongs. A flat, plane, carbide drill tip provided with two cutting edgesis fastened in the slit. On account of this solution, it is possible tocombine higher-grade cutting-edge material with inexpensive, lower-gradecarrier material.

Like drills, end mills are also mainly suitable for absorbing axialforces. In this respect, drills and milling cutters are comparable withone another. For this reason, the abovementioned publication is alsocited as prior art for the present invention.

A disadvantage of the known solution is the low strength, due to theshape, of the shank in the area of the forking. This disadvantage can becompensated for only to a limited extent even by the best joiningtechniques between the cutting-edge carrier and the shank. Theconsequences are unfavourable vibration behaviour, high wear caused bythis at the cutting edges of the tool, rapid fatigue and fracture of theshank as well as inferior cutting or working quality.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved millingtool in which the above-mentioned disadvantages are at least partiallycured or alleviated.

This object, and others which will be made more apparent hereinafter,are attained in a milling tool having a shank having a shank rotationaxis and a flat first cutting-edge carrier having at least one cuttingedge. The cutting-edge carrier is fastened to the shank in a radiallyprojecting, lobe-like manner. The cutting-edge carrier is intended torotate about a carrier rotation axis in its plane.

According to one form of the invention, the milling tool consists of ashank having a shank rotation axis and a substantially flat cutting-edgecarrier having at least one cutting edge and at least two arched areas.The at least two arched areas are shaped and positioned to form atubular socket in which the shank is held so that the cutting-edgecarrier is attached to the shank in a radially projecting lobe-likemanner and is rotatable about the shank rotation axis. The shankrotation axis is arranged in a plane of the substantially flatcutting-edge carrier.

In a preferred embodiment of this form of the invention two arched areasare arched in opposite directions from each other and are displaced fromand parallel to the shank rotation axis to at least partially form thetubular socket.

According to another form of the invention, the milling tool consists ofa shank having a shank rotation axis, a first cutting-edge carrierhaving at least one cutting edge and at least two arched areas and asecond cutting-edge carrier having at least one cutting edge and atleast two arched areas. The arched areas are shaped and positioned toform a tubular socket in which the shank is attached with bothcutting-edge carriers radially projecting in a lob-like manner from theshank rotatable about the shank rotation axis.

In an advantageous modification of this other form of the invention, theat least two arched areas of the first cutting-edge carrier are spacedfrom each other axially, have surfaces normal to the shank rotation axisand arch in the same direction displaced from and parallel to the shankrotation axis and the at least two arched areas of the secondcutting-edge carrier are spaced from each other axially, have surfacesnormal to the shank rotation axis, arch in the same direction displacedfrom and parallel to the shank rotation axis so that the first andsecond cutting-edge carriers mutually overlap to form the tubular socketfor the shank so that, when the shank is attached in the tubular socket,the cutting-edge carriers are locked against each other.

The shank is attached to the cutting-edge carriers or carrier by any ofa number of methods including a crimp joint, a weld joint, a brazedjoint or an adhesively bonded joint.

A milling tool has the advantages that it is particularly simple andinexpensive to manufacture and combines long life with a very high levelof achievable working quality as well as particular user-friendliness.

Finished standardized pins can be used as the shank, and alreadyexisting semi-finished metal plates or plate parts which are simple toproduce can be used as the cutting-edge carrier. The shape of the shankand thus also its strength are not affected by the cutting-edge carrierfastened thereto. The shank therefore keeps its highest possiblestrength based on the shape.

Mounting or assembling the individual parts, already hardened if needby, to form a finished tool can be carried out in a simple manner. Thelow mass of the milling tool permits particularly high rotationalspeeds. The shape of the cutting-edge carriers makes possibleuser-friendly handling with reduced risk of injury in particular whenclamping the milling tool. Out-of-balance after the sharpening isvirtually negligible on account of the shape or the mass distribution ofthe cutting-edge carrier.

BRIEF DESCRIPTION OF THE DRAWING

The invention is explained through exemplary embodiments and is shown inan associated drawing, in which

FIG. 1 is a prospective view of a milling tool having only onecutting-edge carrier,

FIG. 2 shows a side view of it,

FIG. 3 is a plan view of a milling tool having only one cutting-edgecarrier with areas arched several times,

FIGS. 4 and 5 are respectively plan and side views of a milling toolhaving a shank terminating inside only one cutting-edge carrier,

FIG. 6 shows a milling tool having only one cutting-edge carrier whichcarries separate cutting tips,

FIG. 7 is a perspective view of a milling tool having two cutting-edgecarriers and curved safety lobes,

FIG. 8 shows its cross-section,

FIG. 9 shows the exploded representation of a milling tool havingcutting-edge carriers with cutting tips, and

FIG. 10 shows a milling tool having straight safety lobes.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows a milling tool 1 which consists of a cylindrical shank 3and a flat cutting-edge carrier 5. The cutting-edge carrier 5 isprovided with an arched area 7 which emerges from the plane of thecutting-edge carrier 5 in the form of a tube segment and in which theshank 3 is guided and held. In this exemplary embodiment, the remainingarea of the cutting-edge carrier 5 on which the shank 3 rests has aconcavely arched area 8 which is directed in the opposite direction tothe first area 7 and serves to improve the seating of the shank 3 and todistribute the force more uniformly between the shank 3 and thecutting-edge carrier 5.

At its edges furthest away from the axis of the shank 3, thecutting-edge carrier 5 is provided with cutting edges 6, 10. Possiblefurther additional front cutting edges (not shown in the drawing) can bearranged on the end face of the cutting edge carrier 5. The shank 3 canbe designed on one side as a drill (indicated with dot-dashed lines inFIG. 1), which then functions as a center bit for the milling tool 1. Acrimped joint can be produced between the shank 3 and the cutting-edgecarrier 5 via the arched areas 7, 8. However, the crimped joint can alsobe made solely at the shank 3 on each side of the arched areas 7, 8 insuch a way that a positive-locking connection is produced between theshank 3 and the cutting-edge carrier 5. Radial projections P areprovided on the shank 3 in the vicinity of the crimp joint. Otherjoining means can be adhesive bonding, brazing or welding, in particularlaser welding. In FIG. 1 a weld joint W is shown connecting the shank 3to the arched areas 7,8 of the cutting-edge carrier 5. In FIG. 2 abrazed joint B is shown symbolically which connects the shank 3 to thecutting-edge carrier B.

The arched areas 7, 8 which radially embrace the shank 3 are shownparticularly clearly in FIG. 2.

FIG. 3 shows a milling tool 11 whose shank 13 is held on thecutting-edge carrier 15 by additional arched areas 17, 18. At its outeredges, the cutting-edge carrier 15 is provided with cutting edges 16,20.

A milling tool 21 having a shank 23 and a cutting-edge carrier 25 isshown in FIG. 4. The milling tool 21 is provided with arched areas 27,28. One of the arched areas 27, 28 is constructed in such a way that apiece of the cutting-edge carrier 25, as a flat cross member 29 whichhas not been shaped, runs in extension of the axis of the shank 23. Thiscross member 29 serves as an axial stop for the shank 23 and can serveas an additional joining surface for the shank 23. Cutting edges 26, 30are arranged on the outer edges of the cutting-edge carrier 25. Therecan be a welded joint WT between the web 29 and the shank 23. Anadhesive joint A can also be used to connect the shank 13 to thecutting-edge carrier 15.

FIG. 5 shows the side view of the exemplary embodiment in FIG. 4. Here,the profile of the web 29 can be recognized particularly clearly.

An exemplary embodiment of a milling tool 31 in metal plate constructionis shown in a side view in FIG. 6. A shank 33 is guided on acutting-edge carrier 35 between arched areas 37, 38. Cutting edges, 36,40 are arranged on cutting tips 41, 42. The latter are fastened to thecutting-edge carrier 35 on the side moving towards the workpiece duringoperation of the tool by brazing, adhesive bonding or welding.

All exemplary embodiments according to FIGS. 1-6 can be made of sinteredmetal, plate or steel. Differences arise here in the possible joints,depending on the material, between the shank 3, 13, 23, 33 and thecutting-edge carrier 5, 15, 25, 35. Whereas crimped joints can beconveniently and favorable produced for the steel construction,adhesively bonded, brazed or welded joints are more favorable for thesintered-metal construction.

A milling tool 51 shown in FIG. 7 consists of a cylindrical shank 53which has a bevel 54 and carries a first and second cutting-edge carrier55, 59 having a first and second cutting edge 56, 60. The cutting-edgecarrier 55 is provided with an arched area 57 having recesses 63--shownin FIG. 8--and webs 65 remaining between these recesses 63. The secondcutting-edge carrier 59 is likewise provided with an arched area61--shown in FIG. 8--having recesses 63 and crosspieces 65. Thecrosspieces 65 of the first cutting-edge carrier 55 pass through therecesses 63 of the second cutting-edge carrier 59 and, conversely, thecrosspieces 65 of the second cutting-edge carrier 59 pass through therecesses 63 of the first cutting-edge carrier 55. The crosspieces 65curved in opposite directions and overlapping one another form a tubularsocket 67 for accommodating the shank 53.

The cutting edges 56, 60--relative to the axis of the shank 53--arearranged on radially outer end edges of the cutting-edge carriers 55,59. The ends of the cutting-edge carriers 55, 59 opposite the cuttingedges 56, 60 are bent over to form safety lobes 68, 69. The latter areat a clearly smaller distance from the axis of shank 53 than the cuttingedges 56, 60. The safety lobes 68, 69 function on the one hand as a gripsuitable for the hand for inserting the milling cutter 51 into a toolholder and on the other hand as a counterweight for the side of thecutting edges 56, 60. The vibration behaviour of the milling tool 51during its normally very high-speed rotation when milling is therebyimproved. Any out-of-balance caused by the wear of the cutting edges 56,60 is minimized.

Additional front cutting edges (not shown in the drawing) can bearranged, for example, on the end faces of the cutting-tool carriers 55,59.

The cross-section of the milling tool 51 shown in FIG. 8 shows itsS-shaped profile. The safety lobes 68, 69 are bent over at an acuteangle and merge tangentially into the arched areas 57, 61. These mergetangentially on the side facing away from the safety lobes 68, 69 intothe straight cutting-edge carriers 55, 59.

The cutting-tool carriers 75, 79 shown in a further exemplary embodimentin FIG. 9 and having the cutting edges 76, 80 are arranged opposite oneanother in such a way that--by moving towards one another--theircrosspieces 85 move into the recesses 83. The crosspieces 85 overlappingone another in this way together form the socket 87 (shown by brokenline) into which the shank 73 is inserted. The bevel 74 at one end ofthe shank 73 facilitates its insertion into the socket 87.

It is convenient to secure the cutting-edge carriers 75, 79 in terms ofrotation relative to one another and relative to the shank 73 bycrimped, clamped, welded, brazed or adhesively bonded joint. By the useof a slightly conical shank 73 narrowing in the push-in direction, aparticularly good, self-locking interference fit of the shank 73 in thetubular socket 87 formed by the arched areas 77, 81 can be achieved. Thesafety lobes 88, 89 are configured as in the previous exemplaryembodiment.

A particular advantage of the exemplary embodiment according to FIG. 9is that cutting tips 78, 82 made of higher-grade materials can bewelded, adhesively bonded or brazed to the cutting-edge carriers 75, 79made of lower-grade material.

The exemplary embodiment in FIG. 10 shows a milling tool 91 which isprovided with straight safety lobes 108, 109. The other parts, such asshank 93 having bevel 94, first cutting-edge carrier 95 having cuttingedge 96 and arched area 97, second cutting-edge carrier 99 having secondcutting edge 100 and arched area 101 and having recesses 103 as well aswebs 105 form the tool 91 via a tubular socket 107 in the same way asshown in FIGS. 7 to 9.

If a crimped joint is to be produced between the shank 3, 23, 33, 53,73, 93 and the cutting-edge carriers 5, 9, 25, 29, 55, 59, 75, 79, 95,99, this should be made in such a way that the shank is given smallradial projections in the area of the recesses 13, 33, 63, 83, 103.These radial projections help to secure the joint in terms of rotation.

An embodiment of the cutting-edge carriers 5, 9, 25, 29, 55, 59, 75, 95,99 made of sintered metal can be economical especially for high qualityrequirements.

It is of advantage for certain cases if the free end of the shank facingthe workpiece is designed as a drill. This drill then serves as a centerbit for an axially cutting exemplary embodiment (not shown in thedrawing) of a milling tool.

While the invention has been illustrated and described as embodied in amilling tool, it is not intended to be limited to the details shown,since various modifications and structural changes may be made withoutdeparting in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this invention.

What is claimed is new and desired to be protected by Letters Patent isset forth in the appended claims.

We claim:
 1. A milling tool consisting of a shank having a shankrotation axis and a substantially flat cutting-edge carrier having atleast one cutting edge and at least two arched areas, said at least twoarched areas being shaped and positioned to form a tubular socket inwhich said shank is held so that said cutting-edge carrier is attachedto said shank in a radially projecting lobe-like manner and is rotatableabout said shank rotation axis, said shank rotation axis being arrangedin a plane of the substantially flat cutting-edge carrier.
 2. A millingtool as defined in claim 1, wherein two of said arched areas are archedin opposite directions from each other and are displaced parallel to theshank rotation axis to at least partially form the tubular socket.
 3. Amilling tool as defined in claim 1, wherein said cutting-edge carrierhas four of said arched areas arranged in two pairs spaced axially fromeach other, each of said pairs consisting of two of said arched areasarched in opposite directions from each other and are displaced parallelto the shank rotation axis to form the tubular socket.
 4. A milling toolas defined in claim 1, wherein the arched areas are bounded by surfacesnormal to the shank rotation axis.
 5. A milling tool as defined in claim1, wherein the shank is structured like a drill.
 6. A milling tool asdefined in claim 1, wherein the shank is a cylindrical pin and is heldin the tubular socket formed by the arched areas via a crimp joint.
 7. Amilling tool as defined in claim 1, wherein the shank is attached to thecutting-edge carrier by welding.
 8. A milling tool as defined in claim1, wherein the shank is attached to the cutting-edge carrier by a crimpjoint and the shank is provided with a plurality of radial projectionsin the vicinity of the crimp joint.
 9. A milling tool as defined inclaim 1, wherein the shank is attached to the cutting-edge carrier via abrazed joint.
 10. A milling tool as defined in claim 1, wherein thecutting-edge carrier is made of metal plate.
 11. A milling toolconsisting of a shank having a shank rotation axis, a first cutting-edgecarrier having at least one cutting edge and at least two arched areasand a second cutting-edge carrier having at least one cutting edge andat least two arched areas, said arched areas being shaped and positionedto form a tubular socket in which said shank is attached with both ofsaid cutting-edge carriers radially projecting in a lobe-like mannerfrom said shank and being rotatable about said shank rotation axis. 12.A milling tool as defined in claim 11, wherein the shank is attached toat least one of the cutting-edge carriers by a crimp joint.
 13. Amilling tool as defined in claim 12, wherein the shank is provided witha plurality of radial projections in the vicinity of the crimp joint.14. A milling tool as defined in claim 11, wherein the shank is attachedto at least one of the cutting-edge carriers by welding.
 15. A millingtool as defined in claim 11, wherein the shank is attached to at leastone of the cutting-edge carriers by a brazed joint.
 16. A milling toolas defined in claim 11, wherein the shank is attached to at least one ofthe cutting-edge carriers by adhesive means.
 17. A milling tool asdefined in claim 11, wherein the first and second cutting-edge carriersare made of metal plate.
 18. A milling tool as defined in claim 11,wherein the first and second cutting-edge carriers are made of sinteredmetal.
 19. A milling tool as defined in claim 11, wherein the first andsecond cutting-edge carriers have separate cutting tips.
 20. A millingtool as defined in claim 11, wherein the shank is structured like adrill.
 21. A milling tool consisting of a shank having a shank rotationaxis, a first cutting-edge carrier having at least one cutting edge andat least two arched areas and a second cutting-edge carrier having atleast one cutting edge and at least two arched areas, said arched areasbeing shaped and positioned to form a tubular socket in which said shankis attached with both of said cutting-edge carriers radially projectingin a lobe-like manner from said shank and being rotatable about saidshank rotation axis, wherein said at least two arched areas of saidfirst cutting-edge carrier are spaced from each other axially, havesurfaces normal to the shank rotation axis, arch in the same directionand are displaced from and parallel to the shank rotation axis, and saidat least two arched areas of said second cutting-edge carrier are spacedfrom each other axially, have surfaces normal to the shank rotationaxis, are displaced from and parallel to the shank rotation axis andarch in the same direction, so that the first and second cutting-edgecarriers mutually overlap to form the tubular socket for the shank sothat, when said shank is attached in the tubular socket, thecutting-edge carriers are locked against each other.
 22. A milling toolas defined in claim 21, wherein the cutting-edge carriers are providedwith a plurality of crosspieces and recesses and engage in one anotherlike a zip fastener and pass through one another alternately, and saidcrosspieces form the tubular socket for the shank.
 23. A milling tool asdefined in claim 22, wherein the crosspieces are designed to fit therecesses.
 24. A milling tool as defined in claim 23, wherein the shankis a cylindrical pin and is held in the tubular socket via a crimpjoint.
 25. A milling tool as defined in claim 23, wherein the shank is aself-locking cone and is held in the tubular socket in an interferencefit.
 26. A milling tool as defined in claim 25, wherein the cutting-edgecarriers each have a safety lobe without cutting edges located oppositethe cutting edges.
 27. A milling tool as defined in claim 26, whereinthe safety lobes have ends and are rounded off at said ends.
 28. Amilling tool as defined in claim 27, wherein the safety lobes are bentover.